Secondary aims of the study are to 1) determine if improvement with TCA differs between patients below age 65 vs. those aged 65 and above, 2) to determine if improvement with TCA differs by racial/ethnic group (ie., Caucasian, Black, Hispanic), and 3) to determine if improvement with TCA differs by stage of radiographic severity of knee OA at baseline (KL grade 2, 3 or 4)